draft-ietf-ccamp-gmpls-recovery-terminology-05.txt   draft-ietf-ccamp-gmpls-recovery-terminology-06.txt 
CCAMP Working Group CCAMP GMPLS P&R Design Team CCAMP Working Group CCAMP GMPLS P&R Design Team
Internet Draft Internet Draft
Category: Informational Eric Mannie (Editor) Category: Informational Eric Mannie (Editor)
Expiration Date: March 2005 Dimitri Papadimitriou (Editor) Expiration Date: October 2005 Dimitri Papadimitriou (Editor)
October 2004 April 2005
Recovery (Protection and Restoration) Terminology Recovery (Protection and Restoration) Terminology
for Generalized Multi-Protocol Label Switching (GMPLS) for Generalized Multi-Protocol Label Switching (GMPLS)
draft-ietf-ccamp-gmpls-recovery-terminology-05.txt draft-ietf-ccamp-gmpls-recovery-terminology-06.txt
Status of this Memo Status of this Memo
This document is an Internet-Draft and is subject to all provisions This document is an Internet-Draft and is subject to all provisions
of section 3 of RFC 3667. By submitting this Internet-Draft, each of section 3 of RFC 3667. By submitting this Internet-Draft, each
author represents that any applicable patent or other IPR claims of author represents that any applicable patent or other IPR claims of
which he or she is aware have been or will be disclosed, and any of which he or she is aware have been or will be disclosed, and any of
which he or she become aware will be disclosed, in accordance with which he or she become aware will be disclosed, in accordance with
RFC 3668. RFC 3668.
skipping to change at line 41 skipping to change at line 41
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved. Copyright (C) The Internet Society (2005). All Rights Reserved.
Abstract Abstract
This document defines a common terminology for Generalized Multi- This document defines a common terminology for Generalized Multi-
Protocol Label Switching (GMPLS) based recovery mechanisms (i.e. Protocol Label Switching (GMPLS) based recovery mechanisms (i.e.
protection and restoration). The terminology is independent of the protection and restoration). The terminology is independent of the
underlying transport technologies covered by GMPLS. underlying transport technologies covered by GMPLS.
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Status of this Memo .............................................. 1 Status of this Memo .............................................. 1
Abstract ......................................................... 1 Abstract ......................................................... 1
Table of Contents ................................................ 2 Table of Contents ................................................ 2
1. Contributors .................................................. 3 1. Contributors .................................................. 3
2. Introduction .................................................. 3 2. Introduction .................................................. 3
3. Conventions used in this document ............................. 4 3. Conventions used in this document ............................. 4
4. Recovery Terminology Common to Protection and Restoration ..... 4 4. Recovery Terminology Common to Protection and Restoration ..... 4
4.1 Working and Recovery LSP/Span ................................ 5 4.1 Working and Recovery LSP/Span ................................ 5
4.2 Traffic Types ................................................ 5 4.2 Traffic Types ................................................ 5
4.3 LSP/Span Protection and Restoration .......................... 6 4.3 LSP/Span Protection and Restoration .......................... 6
4.4 Recovery Scope ............................................... 6 4.4 Recovery Scope ............................................... 7
4.5 Recovery Domain .............................................. 7 4.5 Recovery Domain .............................................. 7
4.6 Recovery Types ............................................... 7 4.6 Recovery Types ............................................... 7
4.7 Bridge Types ................................................. 9 4.7 Bridge Types ................................................. 9
4.8 Selector Types ............................................... 9 4.8 Selector Types ............................................... 9
4.9 Recovery GMPLS Nodes ........................................ 10 4.9 Recovery GMPLS Nodes ........................................ 10
4.10 Switch-over Mechanism ...................................... 10 4.10 Switch-over Mechanism ...................................... 10
4.11 Reversion operations ....................................... 10 4.11 Reversion operations ....................................... 10
4.12 Failure Reporting .......................................... 11 4.12 Failure Reporting .......................................... 11
4.13 External commands .......................................... 11 4.13 External commands .......................................... 11
4.14 Unidirectional versus Bi-Directional Recovery Switching .... 12 4.14 Unidirectional versus Bi-Directional Recovery Switching .... 12
4.15 Full versus Partial Span Recovery Switching ................ 12 4.15 Full versus Partial Span Recovery Switching ................ 12
4.16 Recovery Schemes Related Time and Durations ................ 13 4.16 Recovery Schemes Related Time and Durations ................ 13
4.17 Impairment ................................................. 13 4.17 Impairment ................................................. 14
4.18 Recovery Ratio ............................................. 14 4.18 Recovery Ratio ............................................. 14
4.19 Hitless Protection Switch-over ............................. 14 4.19 Hitless Protection Switch-over ............................. 14
4.20 Network Survivability ...................................... 14 4.20 Network Survivability ...................................... 14
4.21 Survivable Network ......................................... 14 4.21 Survivable Network ......................................... 14
4.22 Escalation ................................................. 14 4.22 Escalation ................................................. 14
5. Recovery Phases .............................................. 14 5. Recovery Phases .............................................. 14
5.1 Entities Involved During Recovery ........................... 15 5.1 Entities Involved During Recovery ........................... 15
6. Protection Schemes ........................................... 16 6. Protection Schemes ........................................... 16
6.1 1+1 Protection .............................................. 16 6.1 1+1 Protection .............................................. 16
6.2 1:N (N >= 1) Protection ..................................... 16 6.2 1:N (N >= 1) Protection ..................................... 16
6.3 M:N (M, N > 1, N >= M) Protection ........................... 16 6.3 M:N (M, N > 1, N >= M) Protection ........................... 16
6.4 Notes on Protection Schemes ................................. 16 6.4 Notes on Protection Schemes ................................. 17
7. Restoration Schemes .......................................... 17 7. Restoration Schemes .......................................... 17
7.1 Pre-planned LSP Restoration ................................. 17 7.1 Pre-planned LSP Restoration ................................. 17
7.1.1 Shared-Mesh Restoration ................................... 17 7.1.1 Shared-Mesh Restoration ................................... 18
7.2 LSP Restoration ............................................. 18 7.2 LSP Restoration ............................................. 18
7.2.1 Hard LSP Restoration ...................................... 18 7.2.1 Hard LSP Restoration ...................................... 18
7.2.2 Soft LSP Restoration ...................................... 18 7.2.2 Soft LSP Restoration ...................................... 18
8. Security Considerations ...................................... 18 8. Security Considerations ...................................... 18
9. References ................................................... 18 9. IANA Considerations .......................................... 18
9.1 Normative References ........................................ 18 10. References .................................................. 18
9.2 Informative References ...................................... 18 10.1 Normative References ....................................... 18
10. Acknowledgments ............................................. 19 10.2 Informative References ..................................... 19
11. Editor's Address ............................................ 19 11. Acknowledgments ............................................. 20
Intellectual Property Statement ................................. 20 12. Editor's Address ............................................ 20
Disclaimer of Validity .......................................... 20 Intellectual Property Statement ................................. 21
E.Mannie, D.Papadimitriou et al.- Expires March 2005 2 E.Mannie, D.Papadimitriou et al.- Expires October 2005 2
Copyright Statement ............................................. 20 Disclaimer of Validity .......................................... 21
Copyright Statement ............................................. 21
1. Contributors 1. Contributors
This document is the result of the CCAMP Working Group Protection This document is the result of the CCAMP Working Group Protection
and Restoration design team joint effort. The following are the and Restoration design team joint effort. The following are the
authors that contributed to the present document: authors that contributed to the present document:
Deborah Brungard (AT&T) Deborah Brungard (AT&T)
Rm. D1-3C22 - 200 S. Laurel Ave. Rm. D1-3C22 - 200 S. Laurel Ave.
Middletown, NJ 07748, USA Middletown, NJ 07748, USA
EMail: dbrungard@att.com EMail: dbrungard@att.com
Sudheer Dharanikota Sudheer Dharanikota
EMail: sudheer@ieee.org EMail: sudheer@ieee.org
Jonathan P. Lang (Rincon Networks) Jonathan P. Lang (Sonos)
506 Chapala Street
Santa Barbara, CA 93101, USA
EMail: jplang@ieee.org EMail: jplang@ieee.org
Guangzhi Li (AT&T) Guangzhi Li (AT&T)
180 Park Avenue, 180 Park Avenue,
Florham Park, NJ 07932, USA Florham Park, NJ 07932, USA
EMail: gli@research.att.com EMail: gli@research.att.com
Eric Mannie Eric Mannie
EMail: eric_mannie@hotmail.com EMail: eric_mannie@hotmail.com
Dimitri Papadimitriou (Alcatel) Dimitri Papadimitriou (Alcatel)
Fr. Wellesplein, 1 Francis Wellesplein, 1
B-2018, Antwerpen, Belgium B-2018 Antwerpen, Belgium
EMail: dimitri.papadimitriou@alcatel.be EMail: dimitri.papadimitriou@alcatel.be
Bala Rajagopalan Bala Rajagopalan (Intel Broadband Wireless Division)
EMail: braj@earthlink.net 2111 NE 25th Ave.
Hillsboro, OR 97124, USA
EMail: bala.rajagopalan@intel.com
Yakov Rekhter (Juniper) Yakov Rekhter (Juniper)
1194 N. Mathilda Avenue 1194 N. Mathilda Avenue
Sunnyvale, CA 94089, USA Sunnyvale, CA 94089, USA
EMail: yakov@juniper.net EMail: yakov@juniper.net
2. Introduction 2. Introduction
This document defines a common terminology for Generalized Multi- This document defines a common terminology for Generalized Multi-
Protocol Label Switching (GMPLS) based recovery mechanisms (i.e. Protocol Label Switching (GMPLS) based recovery mechanisms (i.e.
protection and restoration) that are under consideration by the protection and restoration).
CCAMP Working Group.
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The terminology proposed in this document is independent of the The terminology proposed in this document is independent of the
underlying transport technologies and borrows from the G.808.1 ITU-T underlying transport technologies and borrows from the G.808.1 ITU-T
Recommendation [G.808.1] and from the G.841 ITU-T Recommendation Recommendation [G.808.1] and from the G.841 ITU-T Recommendation
[G.841]. The restoration terminology and concepts have been gathered [G.841]. The restoration terminology and concepts have been gathered
from numerous sources including IETF drafts. from numerous sources including IETF drafts.
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In the context of this document, the term "recovery" denotes both In the context of this document, the term "recovery" denotes both
protection and restoration. The specific terms "protection" and protection and restoration. The specific terms "protection" and
"restoration" will only be used when differentiation is required. "restoration" will only be used when differentiation is required.
This document focuses on the terminology for the recovery of Label This document focuses on the terminology for the recovery of Label
Switched Paths (LSPs) controlled by a GMPLS control plane. The Switched Paths (LSPs) controlled by a GMPLS control plane. The
proposed terminology applies to end-to-end, segment, and span (i.e. proposed terminology applies to end-to-end, segment, and span (i.e.
link) recovery. Note that the terminology for recovery of the link) recovery. Note that the terminology for recovery of the
control plane itself is not in the scope of this document. control plane itself is not in the scope of this document.
Protection and restoration of switched LSPs under tight time Protection and restoration of switched LSPs under tight time
constraints is a challenging problem. This is particularly relevant constraints is a challenging problem. This is particularly relevant
to optical networks that consist of Time Division Multiplex (TDM) to optical networks that consist of Time Division Multiplex (TDM)
and/or all-optical (photonic) cross-connects referred to as GMPLS and/or all-optical (photonic) cross-connects referred to as GMPLS
nodes (or simply nodes, or even sometimes "Label Switching Routers, nodes (or simply nodes, or even sometimes "Label Switching Routers,
or LSRs") connected in a general topology [GMPLS-ARCH]. or LSRs") connected in a general topology [RFC3945].
Recovery typically involves the activation of a recovery (or Recovery typically involves the activation of a recovery (or
alternate) LSP when a failure is encountered in the working (or alternate) LSP when a failure is encountered in the working LSP.
primary) LSP.
A working or recovery LSP is characterized by an ingress interface, A working or recovery LSP is characterized by an ingress interface,
an egress interface, and a set of intermediate nodes and spans an egress interface, and a set of intermediate nodes and spans
through which the LSP is routed. The working and recovery LSPs are through which the LSP is routed. The working and recovery LSPs are
typically resource disjoint (e.g. node and/or span disjoint). This typically resource disjoint (e.g. node and/or span disjoint). This
ensures that a single failure will not affect both the working and ensures that a single failure will not affect both the working and
recovery LSPs. recovery LSPs.
A bi-directional span between neighboring nodes is usually realized A bi-directional span between neighboring nodes is usually realized
as a pair of unidirectional spans. The end-to-end path for a bi- as a pair of unidirectional spans. The end-to-end path for a bi-
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The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in [RFC2119]. this document are to be interpreted as described in [RFC2119].
4. Recovery Terminology Common to Protection and Restoration 4. Recovery Terminology Common to Protection and Restoration
This section defines the following general terms common to both This section defines the following general terms common to both
protection and restoration (i.e. recovery). In addition, most of protection and restoration (i.e. recovery). In addition, most of
these terms apply to end-to-end, segment and span LSP recovery. Note these terms apply to end-to-end, segment and span LSP recovery. Note
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that span recovery does not protect the nodes at each end of the that span recovery does not protect the nodes at each end of the
span, otherwise end-to-end or segment LSP recovery should be used. span, otherwise end-to-end or segment LSP recovery should be used.
The terminology and the definitions have been originally taken from The terminology and the definitions have been originally taken from
[G.808.1]. However, for generalization, the following language that [G.808.1]. However, for generalization, the following language that
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is not directly related to recovery has been adapted to GMPLS and is not directly related to recovery has been adapted to GMPLS and
the common IETF terminology: the common IETF terminology:
An LSP is used as a generic term to designate either an SNC (Sub- An LSP is used as a generic term to designate either an SNC (Sub-
Network Connection) or an NC (Network Connection) in ITU-T Network Connection) or an NC (Network Connection) in ITU-T
terminology. The ITU-T uses the term transport entity to designate terminology. The ITU-T uses the term transport entity to designate
either a link, an SNC or an NC. The term "Traffic" is used instead either a link, an SNC or an NC. The term "Traffic" is used instead
of "Traffic Signal". The term protection or restoration "scheme" is of "Traffic Signal". The term protection or restoration "scheme" is
used instead of protection or restoration "architecture". used instead of protection or restoration "architecture".
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LSP/span) when these resources are not being used for the recovery LSP/span) when these resources are not being used for the recovery
of normal traffic; i.e. when the recovery resources are in standby of normal traffic; i.e. when the recovery resources are in standby
mode. When the recovery resources are required to recover normal mode. When the recovery resources are required to recover normal
traffic from the failed working LSP/span, the extra traffic is pre- traffic from the failed working LSP/span, the extra traffic is pre-
empted. Extra traffic is not protected by definition, but may be empted. Extra traffic is not protected by definition, but may be
restored. Moreover, extra traffic does not need to commence or be restored. Moreover, extra traffic does not need to commence or be
terminated at the ends of the LSPs/spans that it uses. terminated at the ends of the LSPs/spans that it uses.
C. Null traffic: C. Null traffic:
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Traffic carried over the recovery LSP/span if it is not used to Traffic carried over the recovery LSP/span if it is not used to
carry normal or extra traffic. Null traffic can be any kind of carry normal or extra traffic. Null traffic can be any kind of
traffic that conforms to the signal structure of the specific layer, traffic that conforms to the signal structure of the specific layer,
and it is ignored (not selected) at the egress of the recovery and it is ignored (not selected) at the egress of the recovery
LSP/span. LSP/span.
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4.3 LSP/Span Protection and Restoration 4.3 LSP/Span Protection and Restoration
The following subtle distinction is generally made between the terms The following subtle distinction is generally made between the terms
"protection" and "restoration", even though these terms are often "protection" and "restoration", even though these terms are often
used interchangeably [RFC3386]. used interchangeably [RFC3386].
The distinction between protection and restoration is made based on The distinction between protection and restoration is made based on
the resource allocation done during the recovery LSP/span the resource allocation done during the recovery LSP/span
establishment. The distinction between different types of establishment. The distinction between different types of
restoration is made based on the level of route computation, restoration is made based on the level of route computation,
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resources may be pre-computed, signaled and selected a priori, but resources may be pre-computed, signaled and selected a priori, but
not cross-connected to restore a working LSP/span. The complete not cross-connected to restore a working LSP/span. The complete
establishment of the restoration LSP/span occurs only after a establishment of the restoration LSP/span occurs only after a
failure of the working LSP/span, and requires some additional failure of the working LSP/span, and requires some additional
signaling. signaling.
Both protection and restoration require signaling. Signaling to Both protection and restoration require signaling. Signaling to
establish the recovery resources and signaling associated with the establish the recovery resources and signaling associated with the
use of the recovery LSP(s)/span(s) are needed. use of the recovery LSP(s)/span(s) are needed.
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4.4 Recovery Scope 4.4 Recovery Scope
Recovery can be applied at various levels throughout the network. An Recovery can be applied at various levels throughout the network. An
LSP may be subject to local (span), segment, and/or end-to-end LSP may be subject to local (span), segment, and/or end-to-end
recovery. recovery.
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Local (span) recovery refers to the recovery of an LSP over a link Local (span) recovery refers to the recovery of an LSP over a link
between two nodes. between two nodes.
End-to-end recovery refers to the recovery of an entire LSP from its End-to-end recovery refers to the recovery of an entire LSP from its
source (ingress node end-point) to its destination (egress node end- source (ingress node end-point) to its destination (egress node end-
point). point).
Segment recovery refers to the recovery over a portion of the Segment recovery refers to the recovery over a portion of the
network of a segment LSP (i.e. an SNC in the ITU-T terminology) of network of a segment LSP (i.e. an SNC in the ITU-T terminology) of
an end-to-end LSP. Such recovery protects against span and/or node an end-to-end LSP. Such recovery protects against span and/or node
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One dedicated protection LSP/span protects exactly one working One dedicated protection LSP/span protects exactly one working
LSP/span and the normal traffic is permanently duplicated at the LSP/span and the normal traffic is permanently duplicated at the
ingress node on both the working and protection LSPs/spans. No extra ingress node on both the working and protection LSPs/spans. No extra
traffic can be carried over the protection LSP/span. traffic can be carried over the protection LSP/span.
This type is applicable to LSP/span protection, but not to LSP/span This type is applicable to LSP/span protection, but not to LSP/span
restoration. restoration.
B. 0:1 type: unprotected B. 0:1 type: unprotected
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No specific recovery LSP/span protects the working LSP/span. No specific recovery LSP/span protects the working LSP/span.
However, the working LSP/span can potentially be restored through However, the working LSP/span can potentially be restored through
any alternate available route/span, with or without any pre-computed any alternate available route/span, with or without any pre-computed
restoration route. Note that there are no resources pre-established restoration route. Note that there are no resources pre-established
for this recovery type. for this recovery type.
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This type is applicable to LSP/span restoration, but not to LSP/span This type is applicable to LSP/span restoration, but not to LSP/span
protection. Span restoration can be for instance achieved by moving protection. Span restoration can be for instance achieved by moving
all the LSPs transported over of a failed span to a dynamically all the LSPs transported over of a failed span to a dynamically
selected span. selected span.
C. 1:1 type: dedicated recovery with extra traffic C. 1:1 type: dedicated recovery with extra traffic
One specific recovery LSP/span protects exactly one specific working One specific recovery LSP/span protects exactly one specific working
LSP/span but the normal traffic is transmitted only over one LSP LSP/span but the normal traffic is transmitted only over one LSP
(working or recovery) at a time. Extra traffic can be transported (working or recovery) at a time. Extra traffic can be transported
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as a recovery scheme. The choice of X is a network resource as a recovery scheme. The choice of X is a network resource
management policy decision. management policy decision.
E. M:N (M, N > 1, N >= M) type: E. M:N (M, N > 1, N >= M) type:
A set of M specific recovery LSPs/spans protects a set of up to N A set of M specific recovery LSPs/spans protects a set of up to N
specific working LSPs/spans. The two sets are explicitly identified. specific working LSPs/spans. The two sets are explicitly identified.
Extra traffic can be transported over the M recovery LSPs/spans when Extra traffic can be transported over the M recovery LSPs/spans when
available. All the LSPs/spans must start and end at the same nodes. available. All the LSPs/spans must start and end at the same nodes.
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Sometimes, the working LSPs/spans are assumed to be resource Sometimes, the working LSPs/spans are assumed to be resource
disjoint in the network so that they do not share any failure disjoint in the network so that they do not share any failure
probability, but this is not mandatory. Obviously, if several probability, but this is not mandatory. Obviously, if several
working LSPs/spans in the set of N are concurrently affected by some working LSPs/spans in the set of N are concurrently affected by some
failure(s), the traffic on only M of these failed LSPs/spans may be failure(s), the traffic on only M of these failed LSPs/spans may be
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recovered. Note that N can be arbitrarily large (i.e. infinite). The recovered. Note that N can be arbitrarily large (i.e. infinite). The
choice of N and M is a policy decision. choice of N and M is a policy decision.
This type is applicable to LSP/span protection and LSP restoration, This type is applicable to LSP/span protection and LSP restoration,
but not to span restoration. but not to span restoration.
4.7 Bridge Types 4.7 Bridge Types
A bridge is the function that connects the normal traffic and extra A bridge is the function that connects the normal traffic and extra
traffic to the working and recovery LSP/span. traffic to the working and recovery LSP/span.
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A. Selective selector A. Selective selector
Is a selector that extracts the normal traffic from either the Is a selector that extracts the normal traffic from either the
working LSP/span output or the recovery LSP/span output. working LSP/span output or the recovery LSP/span output.
B. Merging selector B. Merging selector
For 1:N and M:N protection types, the selector permanently extracts For 1:N and M:N protection types, the selector permanently extracts
the normal traffic from both the working and recovery LSP/span the normal traffic from both the working and recovery LSP/span
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outputs. This alternative works only in combination with a selector outputs. This alternative works only in combination with a selector
bridge. bridge.
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4.9 Recovery GMPLS Nodes 4.9 Recovery GMPLS Nodes
This section defines the GMPLS nodes involved during recovery. This section defines the GMPLS nodes involved during recovery.
A. Ingress GMPLS node of an end-to-end LSP/segment LSP/span A. Ingress GMPLS node of an end-to-end LSP/segment LSP/span
The ingress node of an end-to-end LSP/segment LSP/span is where the The ingress node of an end-to-end LSP/segment LSP/span is where the
normal traffic may be bridged to the recovery end-to-end LSP/segment normal traffic may be bridged to the recovery end-to-end LSP/segment
LSP/span. Also known as source node in the ITU-T terminology. LSP/span. Also known as source node in the ITU-T terminology.
skipping to change at line 527 skipping to change at line 529
LSP/span, the action of connecting the normal traffic to the LSP/span, the action of connecting the normal traffic to the
recovery LSP/span. recovery LSP/span.
4.11 Reversion operations 4.11 Reversion operations
A revertive recovery operation refers to a recovery switching A revertive recovery operation refers to a recovery switching
operation, where the traffic returns to (or remains on) the working operation, where the traffic returns to (or remains on) the working
LSP/span if the switch-over requests are terminated; i.e. when the LSP/span if the switch-over requests are terminated; i.e. when the
working LSP/span has recovered from the failure. working LSP/span has recovered from the failure.
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Therefore a non-revertive recovery switching operation is when the Therefore a non-revertive recovery switching operation is when the
traffic does not return to the working LSP/span if the switch-over traffic does not return to the working LSP/span if the switch-over
requests are terminated. requests are terminated.
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4.12 Failure Reporting 4.12 Failure Reporting
This section gives (for information) several signal types commonly This section gives (for information) several signal types commonly
used in transport planes to report a failure condition. Note that used in transport planes to report a failure condition. Note that
fault reporting may require additional signaling mechanisms. fault reporting may require additional signaling mechanisms.
A. Signal Degrade (SD): a signal indicating that the associated data A. Signal Degrade (SD): a signal indicating that the associated data
has degraded. has degraded.
B. Signal Fail (SF): a signal indicating that the associated data B. Signal Fail (SF): a signal indicating that the associated data
skipping to change at line 556 skipping to change at line 557
associated group data has degraded. associated group data has degraded.
D. Signal Fail Group (SFG): a signal indicating that the associated D. Signal Fail Group (SFG): a signal indicating that the associated
group has failed. group has failed.
Note: SDG and SFG definitions are under discussion at the ITU-T. Note: SDG and SFG definitions are under discussion at the ITU-T.
4.13 External commands 4.13 External commands
This section defines several external commands, typically issued by This section defines several external commands, typically issued by
an operator through the NMS/EMS, which can be used to influence or an operator through the Network Management System (NMS)/Element
command the recovery schemes. Management System (EMS), which can be used to influence or command
the recovery schemes.
A. Lockout of recovery LSP/span: A. Lockout of recovery LSP/span:
A configuration action initiated externally that results in the A configuration action initiated externally that results in the
recovery LSP/span being temporarily unavailable to transport traffic recovery LSP/span being temporarily unavailable to transport traffic
(either normal or extra traffic). (either normal or extra traffic).
B. Lockout of normal traffic: B. Lockout of normal traffic:
A configuration action initiated externally that results in the A configuration action initiated externally that results in the
skipping to change at line 580 skipping to change at line 582
allowed on the recovery LSP/span. allowed on the recovery LSP/span.
C. Freeze: C. Freeze:
A configuration action initiated externally that prevents any A configuration action initiated externally that prevents any
switch-over action to be taken, and as such freezes the current switch-over action to be taken, and as such freezes the current
state. state.
D. Forced switch-over for normal traffic: D. Forced switch-over for normal traffic:
E.Mannie, D.Papadimitriou et al.- Expires October 2005 11
A switch-over action initiated externally that switches normal A switch-over action initiated externally that switches normal
traffic to the recovery LSP/span, unless an equal or higher priority traffic to the recovery LSP/span, unless an equal or higher priority
switch-over command is in effect. switch-over command is in effect.
E. Manual switch-over for normal traffic: E. Manual switch-over for normal traffic:
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A switch-over action initiated externally that switches normal A switch-over action initiated externally that switches normal
traffic to the recovery LSP/span, unless a fault condition exists on traffic to the recovery LSP/span, unless a fault condition exists on
other LSPs/spans (including the recovery LSP/span) or an equal or other LSPs/spans (including the recovery LSP/span) or an equal or
higher priority switch-over command is in effect. higher priority switch-over command is in effect.
F. Manual switch-over for recovery LSP/span: F. Manual switch-over for recovery LSP/span:
A switch-over action initiated externally that switches normal A switch-over action initiated externally that switches normal
traffic to the working LSP/span, unless a fault condition exists on traffic to the working LSP/span, unless a fault condition exists on
the working LSP/span or an equal or higher priority switch-over the working LSP/span or an equal or higher priority switch-over
skipping to change at line 633 skipping to change at line 635
notification or bulk failure notification of the S LSPs carried by notification or bulk failure notification of the S LSPs carried by
this span. In either case, the corresponding recovery switching this span. In either case, the corresponding recovery switching
actions are performed at the LSP level such that the ratio between actions are performed at the LSP level such that the ratio between
the number of recovery switching messages and the number of the number of recovery switching messages and the number of
recovered LSP (in one given direction) is minimized. If this ratio recovered LSP (in one given direction) is minimized. If this ratio
equals 1, one refers to full span recovery, otherwise, if this ratio equals 1, one refers to full span recovery, otherwise, if this ratio
is greater than 1 one refers to partial span recovery. is greater than 1 one refers to partial span recovery.
A. Full Span Recovery A. Full Span Recovery
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All the S LSP carried over a given span are recovered under span All the S LSP carried over a given span are recovered under span
failure condition. Full span recovery is also referred to as "bulk failure condition. Full span recovery is also referred to as "bulk
recovery". recovery".
B. Partial Span Recovery B. Partial Span Recovery
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Only a subset s of the S LSP carried over a given span are recovered Only a subset s of the S LSP carried over a given span are recovered
under span failure condition. Both selection criteria of the under span failure condition. Both selection criteria of the
entities belonging to this subset and the decision concerning the entities belonging to this subset and the decision concerning the
recovery of the remaining (S - s) LSP are based on local policy. recovery of the remaining (S - s) LSP are based on local policy.
4.16 Recovery Schemes Related Time and Durations 4.16 Recovery Schemes Related Time and Durations
This section gives several typical timing definitions that are of This section gives several typical timing definitions that are of
importance for recovery schemes. importance for recovery schemes.
skipping to change at line 685 skipping to change at line 687
The total recovery time is defined as the sum of the detection, the The total recovery time is defined as the sum of the detection, the
correlation, the notification and the recovery switching time. correlation, the notification and the recovery switching time.
F. Wait To Restore time: F. Wait To Restore time:
A period of time that must elapse from a recovered fault before an A period of time that must elapse from a recovered fault before an
LSP/span can be used again to transport the normal traffic and/or to LSP/span can be used again to transport the normal traffic and/or to
select the normal traffic from. select the normal traffic from.
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Note: the hold-off time is defined as the time between the reporting Note: the hold-off time is defined as the time between the reporting
of signal fail or degrade, and the initialization of the recovery of signal fail or degrade, and the initialization of the recovery
switching operation. This is useful when multiple layers of recovery switching operation. This is useful when multiple layers of recovery
are being used. are being used.
4.17 Impairment 4.17 Impairment
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A defect or performance degradation, which may lead to SF or SD A defect or performance degradation, which may lead to SF or SD
trigger. trigger.
4.18 Recovery Ratio 4.18 Recovery Ratio
The quotient of the actually recovery bandwidth divided by the The quotient of the actually recovery bandwidth divided by the
traffic bandwidth which is intended to be protected. traffic bandwidth which is intended to be protected.
4.19 Hitless Protection Switch-over 4.19 Hitless Protection Switch-over
Protection switch-over, which does not cause data loss, data Protection switch-over, which does not cause data loss, data
duplication, data disorder, or bit errors upon recovery switching duplication, data disorder, or bit errors upon recovery switching
action. action.
4.20 Network Survivability 4.20 Network Survivability
The set of capabilities that allow a network to restore affected The set of capabilities that allow a network to restore affected
traffic in the event of a failure. The degree of survivability is traffic in the event of a failure. The degree of survivability is
determined by the networks capability to survive single and determined by the network's capability to survive single and
multiple failures. multiple failures.
4.21 Survivable Network 4.21 Survivable Network
A network that is capable of restoring traffic in the event of a A network that is capable of restoring traffic in the event of a
failure. failure.
4.22 Escalation 4.22 Escalation
A network survivability action caused by the impossibility of the A network survivability action caused by the impossibility of the
skipping to change at line 739 skipping to change at line 741
- Phase 1: Failure Detection - Phase 1: Failure Detection
The action of detecting the impairment (defect of performance The action of detecting the impairment (defect of performance
degradation) as a defect condition and consequential activation of degradation) as a defect condition and consequential activation of
SF or SD trigger to the control plane (through internal interface SF or SD trigger to the control plane (through internal interface
with the transport plane). Thus, failure detection (that should with the transport plane). Thus, failure detection (that should
occur at the transport layer closest to the failure) is the only occur at the transport layer closest to the failure) is the only
phase that can not be achieved by the control plane alone. phase that can not be achieved by the control plane alone.
E.Mannie, D.Papadimitriou et al.- Expires October 2005 14
- Phase 2: Failure Localization (and Isolation) - Phase 2: Failure Localization (and Isolation)
Failure localization provides to the deciding entity information Failure localization provides to the deciding entity information
about the location (and so the identity) of the transport plane about the location (and so the identity) of the transport plane
entity that causes the LSP(s)/span(s) failure. The deciding entity entity that causes the LSP(s)/span(s) failure. The deciding entity
E.Mannie, D.Papadimitriou et al.- Expires March 2005 14
can then take accurate decision to achieve finer grained recovery can then take accurate decision to achieve finer grained recovery
switching action(s). switching action(s).
- Phase 3: Failure Notification - Phase 3: Failure Notification
Failure notification phase is used 1) to inform intermediate nodes Failure notification phase is used 1) to inform intermediate nodes
that LSP(s)/span(s) failure has occurred and has been detected 2) to that LSP(s)/span(s) failure has occurred and has been detected 2) to
inform the recovery deciding entities (which can correspond to any inform the recovery deciding entities (which can correspond to any
intermediate or end-point of the failed LSP/span) that the intermediate or end-point of the failed LSP/span) that the
corresponding LSP/span is not available. corresponding LSP/span is not available.
skipping to change at line 792 skipping to change at line 793
and report the failure to the deciding entity. Fault reporting can and report the failure to the deciding entity. Fault reporting can
be automatically performed by the deciding entity detecting the be automatically performed by the deciding entity detecting the
failure. failure.
C. Deciding Entity (part of the failure recovery decision process): C. Deciding Entity (part of the failure recovery decision process):
An entity that makes the recovery decision or selects the recovery An entity that makes the recovery decision or selects the recovery
resources. This entity communicates the decision to the impacted resources. This entity communicates the decision to the impacted
LSPs/spans with the recovery actions to be performed. LSPs/spans with the recovery actions to be performed.
E.Mannie, D.Papadimitriou et al.- Expires October 2005 15
D. Recovering Entity (part of the failure recovery activation D. Recovering Entity (part of the failure recovery activation
process): process):
An entity that participates in the recovery of the LSPs/spans. An entity that participates in the recovery of the LSPs/spans.
E.Mannie, D.Papadimitriou et al.- Expires March 2005 15
The process of moving failed LSPs from a failed (working) span to a The process of moving failed LSPs from a failed (working) span to a
protection span must be initiated by one of the nodes terminating protection span must be initiated by one of the nodes terminating
the span, e.g. A or B. The deciding (and recovering) entity is the span, e.g. A or B. The deciding (and recovering) entity is
referred to as the "master" while the other node is called the referred to as the "master" while the other node is called the
"slave" and corresponds to a recovering only entity. "slave" and corresponds to a recovering only entity.
Note: The determination of the master and the slave may be based on Note: The determination of the master and the slave may be based on
configured information or protocol specific requirements. configured information or protocol specific requirements.
6. Protection Schemes 6. Protection Schemes
skipping to change at line 844 skipping to change at line 845
Unprotected extra traffic can be transported over the protection Unprotected extra traffic can be transported over the protection
LSP/span whenever the protection LSP/span is not used to carry a LSP/span whenever the protection LSP/span is not used to carry a
normal traffic. normal traffic.
6.3 M:N (M, N > 1, N >= M) Protection 6.3 M:N (M, N > 1, N >= M) Protection
M:N protection has N working LSPs/spans carrying normal traffic and M:N protection has N working LSPs/spans carrying normal traffic and
M protection LSP/span that may carry extra-traffic. M protection LSP/span that may carry extra-traffic.
E.Mannie, D.Papadimitriou et al.- Expires October 2005 16
At the ingress, the normal traffic is either permanently connected At the ingress, the normal traffic is either permanently connected
to its working LSP/span and may be connected to one of the to its working LSP/span and may be connected to one of the
protection LSPs/spans (case of broadcast bridge), or is connected to protection LSPs/spans (case of broadcast bridge), or is connected to
either its working or one of the protection LSPs/spans (case of either its working or one of the protection LSPs/spans (case of
selector bridge). At the egress node, the normal traffic is selected selector bridge). At the egress node, the normal traffic is selected
from either its working or one of the protection LSP/span. from either its working or one of the protection LSP/span.
E.Mannie, D.Papadimitriou et al.- Expires March 2005 16
Unprotected extra traffic can be transported over the M protection Unprotected extra traffic can be transported over the M protection
LSP/span whenever the protection LSPs/spans is not used to carry a LSP/span whenever the protection LSPs/spans is not used to carry a
normal traffic. normal traffic.
6.4 Notes on Protection Schemes 6.4 Notes on Protection Schemes
All protection types are either uni- or bi-directional, obviously, All protection types are either uni- or bi-directional, obviously,
the latter applies only to bi-directional LSP/span and requires the latter applies only to bi-directional LSP/span and requires
coordination between the ingress and egress node during protection coordination between the ingress and egress node during protection
switching. switching.
skipping to change at line 897 skipping to change at line 898
working LSP and requires some additional restoration signaling. working LSP and requires some additional restoration signaling.
Therefore, this mechanism protects against working LSP failure(s) Therefore, this mechanism protects against working LSP failure(s)
but requires activation of the restoration LSP after failure but requires activation of the restoration LSP after failure
occurrence. After the ingress node has activated the restoration occurrence. After the ingress node has activated the restoration
LSP, the latter can carry the normal traffic. LSP, the latter can carry the normal traffic.
Note: when each working LSP is recoverable by exactly one Note: when each working LSP is recoverable by exactly one
restoration LSP, one refers also to 1:1 (pre-planned) re-routing restoration LSP, one refers also to 1:1 (pre-planned) re-routing
without extra-traffic. without extra-traffic.
E.Mannie, D.Papadimitriou et al.- Expires October 2005 17
7.1.1 Shared-Mesh Restoration 7.1.1 Shared-Mesh Restoration
"Shared-mesh" restoration is defined as a particular case of pre- "Shared-mesh" restoration is defined as a particular case of pre-
planned LSP re-routing that reduces the restoration resource planned LSP re-routing that reduces the restoration resource
requirements by allowing multiple restoration LSPs (initiated from requirements by allowing multiple restoration LSPs (initiated from
E.Mannie, D.Papadimitriou et al.- Expires March 2005 17
distinct ingress nodes) to share common resources (including links distinct ingress nodes) to share common resources (including links
and nodes.) and nodes.)
7.2 LSP Restoration 7.2 LSP Restoration
Also referred to as LSP re-routing. The ingress node switches the Also referred to as LSP re-routing. The ingress node switches the
normal traffic to an alternate LSP signaled and fully established normal traffic to an alternate LSP signaled and fully established
(i.e. cross-connected) after failure detection and/or notification. (i.e. cross-connected) after failure detection and/or notification.
The alternate LSP path may be computed after failure detection The alternate LSP path may be computed after failure detection
and/or notification. In this case, one also refers to "Full LSP Re- and/or notification. In this case, one also refers to "Full LSP Re-
skipping to change at line 934 skipping to change at line 935
alternate LSP (i.e. break-before-make). alternate LSP (i.e. break-before-make).
7.2.2 Soft LSP Restoration 7.2.2 Soft LSP Restoration
Also referred to as soft LSP re-routing. A re-routing operation Also referred to as soft LSP re-routing. A re-routing operation
where the LSP is released after the full establishment of an where the LSP is released after the full establishment of an
alternate LSP (i.e. make-before-break). alternate LSP (i.e. make-before-break).
8. Security Considerations 8. Security Considerations
This document does not introduce or imply any specific security Security considerations are detailed in [ANAL] and [FUNCT].
consideration.
9. References 9. IANA Considerations
9.1 Normative References This document defines no new code points and requires no action by
IANA.
10. References
10.1 Normative References
[ANAL] D.Papadimitriou and E.Mannie (Editors), "Analysis of
Generalized Multi-Protocol Label Switching (GMPLS)-
based Recovery Mechanisms (including Protection and
Restoration)", Internet Draft (Work in progress), April
2005.
E.Mannie, D.Papadimitriou et al.- Expires October 2005 18
[FUNCT] J.P.Lang, B.Rajagopalan and D.Papadimitriou (Editors),
"Generalized MPLS Recovery Functional Specification,"
Internet Draft (Work in progress), April 2005.
[RFC2026] S.Bradner, "The Internet Standards Process -- Revision [RFC2026] S.Bradner, "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, October 1996. 3", BCP 9, RFC 2026, October 1996.
[RFC2119] S.Bradner, "Key words for use in RFCs to Indicate [RFC2119] S.Bradner, "Key words for use in RFCs to Indicate
Requirement Levels," BCP 14, RFC 2119, March 1997. Requirement Levels," BCP 14, RFC 2119, March 1997.
[RFC3667] S.Bradner, "IETF Rights in Contributions", BCP 78, [RFC3667] S.Bradner, "IETF Rights in Contributions", BCP 78,
RFC 3667, February 2004. RFC 3667, February 2004.
[RFC3668] S.Bradner, Ed., "Intellectual Property Rights in IETF [RFC3668] S.Bradner, Ed., "Intellectual Property Rights in IETF
Technology", BCP 79, RFC 3668, February 2004. Technology", BCP 79, RFC 3668, February 2004.
9.2 Informative References 10.2 Informative References
E.Mannie, D.Papadimitriou et al.- Expires March 2005 18
[GMPLS-ARCH] E.Mannie (Editor), "Generalized MPLS Architecture,"
Internet Draft, Work in progress, draft-ietf-ccamp-
gmpls-architecture-07.txt, May 2003.
[RFC3386] W.S.Lai, et al., "Network Hierarchy and Multilayer [RFC3386] W.S.Lai, et al., "Network Hierarchy and Multilayer
Survivability," RFC 3386, November 2002. Survivability," RFC 3386, November 2002.
[RFC3945] E.Mannie (Editor), "Generalized Multi-Protocol Label
Switching (GMPLS) Architecture," RFC 3945, October
2004.
[T1.105] ANSI, "Synchronous Optical Network (SONET): Basic [T1.105] ANSI, "Synchronous Optical Network (SONET): Basic
Description Including Multiplex Structure, Rates, and Description Including Multiplex Structure, Rates, and
Formats," ANSI T1.105, January 2001. Formats," ANSI T1.105, January 2001.
For information on the availability of the following documents, For information on the availability of the following documents,
please see http://www.itu.int please see http://www.itu.int
[G.707] ITU-T, "Network Node Interface for the Synchronous [G.707] ITU-T, "Network Node Interface for the Synchronous
Digital Hierarchy (SDH)," Recommendation G.707, October Digital Hierarchy (SDH)," Recommendation G.707, October
2000. 2000.
[G.783] ITU-T, "Characteristics of Synchronous Digital [G.783] ITU-T, "Characteristics of Synchronous Digital
Hierarchy (SDH) Equipment Functional Blocks," Hierarchy (SDH) Equipment Functional Blocks,"
Recommendation G.783, October 2000. Recommendation G.783, October 2000.
[G.806] ITU-T, "Characteristics of Transport Equipment [G.806] ITU-T, "Characteristics of Transport Equipment -
Description Methodology and Generic Functionality," Description Methodology and Generic Functionality,"
Recommendation G.806, October 2000. Recommendation G.806, October 2000.
[G.808.1] ITU-T, "Generic Protection Switching Linear trail and [G.808.1] ITU-T, "Generic Protection Switching - Linear trail and
subnetwork protection," Recommendation G.808.1, subnetwork protection," Recommendation G.808.1,
December 2003. December 2003.
[G.841] ITU-T, "Types and Characteristics of SDH Network [G.841] ITU-T, "Types and Characteristics of SDH Network
Protection Architectures," Recommendation G.841, Protection Architectures," Recommendation G.841,
October 1998. October 1998.
E.Mannie, D.Papadimitriou et al.- Expires October 2005 19
[G.842] ITU-T, "Interworking of SDH network protection [G.842] ITU-T, "Interworking of SDH network protection
architectures," Recommendation G.842, October 1998. architectures," Recommendation G.842, October 1998.
10. Acknowledgments 11. Acknowledgments
Many thanks to Adrian Farrel for having thoroughly review this Many thanks to Adrian Farrel for having thoroughly review this
document. document.
11. Editor's Addresses 12. Editor's Addresses
Eric Mannie Eric Mannie
EMail: eric_mannie@hotmail.com EMail: eric_mannie@hotmail.com
Dimitri Papadimitriou (Alcatel) Dimitri Papadimitriou
Alcatel
Francis Wellesplein, 1 Francis Wellesplein, 1
B-2018 Antwerpen, Belgium B-2018 Antwerpen, Belgium
Phone: +32 3 240-8491 Phone: +32 3 240-8491
EMail: dimitri.papadimitriou@alcatel.be EMail: dimitri.papadimitriou@alcatel.be
E.Mannie, D.Papadimitriou et al.- Expires March 2005 19 E.Mannie, D.Papadimitriou et al.- Expires October 2005 20
Intellectual Property Statement Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed Intellectual Property Rights or other rights that might be claimed
to pertain to the implementation or use of the technology described to pertain to the implementation or use of the technology described
in this document or the extent to which any license under such in this document or the extent to which any license under such
rights might or might not be available; nor does it represent that rights might or might not be available; nor does it represent that
it has made any independent effort to identify any such rights. it has made any independent effort to identify any such rights.
Information on the procedures with respect to rights in RFC Information on the procedures with respect to rights in RFC
skipping to change at line 1047 skipping to change at line 1064
This document and the information contained herein are provided on This document and the information contained herein are provided on
an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE
INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement Copyright Statement
Copyright (C) The Internet Society (2004). This document is subject Copyright (C) The Internet Society (2005). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is currently provided by the
Internet Society. Internet Society.
E.Mannie, D.Papadimitriou et al.- Expires March 2005 20 E.Mannie, D.Papadimitriou et al.- Expires October 2005 21
 End of changes. 

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